The present invention relates to a method of manufacturing a sealing apparatus for sealing the gap between two relatively rotating members, and also relates to a mold suitable for use in the application of the method.
An example of a conventional apparatus of the above-mentioned type is shown in FIG. 1. The sealing apparatus 100 shown in the figure includes a first sealing ring 102 having a first sealing lip 101 formed of a rubber-like elastic material, and a second sealing ring 104 having a second sealing lip 103 formed of a resin material and provided to back up the atmospheric side of the first sealing lip 101. By virtue of this arrangement in which the sealing lip 101 formed of a rubber-like elastic material is backed up by the sealing lip formed of a resin material, the sealing apparatus has an enhanced level of pressure resistance and, hence, is applicable to a sealing portion of, e.g., a compressor or a pump where the sealing apparatus used must exhibit a certain level of pressure resistance.
A conventional sealing apparatus, such as that 100 described above, has hitherto been manufactured by separately forming the first sealing ring 102 having the sealing lip 101 formed of a rubber-like elastic material, and the second sealing ring 104 having the sealing lip 103 formed of a resin, and thereafter by integrally combining the formed sealing rings 102 and 104.
In the above-described prior art, it is sometimes desired that the sealing ability should be enhanced by forming a thread in the resin formed sealing lip 103. In previous practice, when such a thread is to be formed, either a cutting operation employing, e.g., a lathe, or a plastic working such as rolling is conducted. However, this has lead to an increase in the number of processes required to prepare the resin formed sealing lip 103 and, hence, to an increase in production cost.